Electrical heating element



Patented Sept. 27, 1932 PATENT OFFICE UNITED STATES GEORGE BBAY, OFLEEDS, ENGLAND, ASSIGNOB T GEO. BRAY 8c COMPANY LIMITED,

015 LEEDS, ENGLAND ELECTRICAL HEATING ELEMENT No Drawing. I Applicationfiled January 28, 1931, Serial No. 511,910, and in Great BritainFebruary 8, 1930.

This invention relates to electrical heating elements of the typecomprising a resistor enveloped in a mass of refractory materialenclosed within a shallow sheet metal casing or sheathing. I

The sheet metal casing or sheathing has been made of a chrome iron orsteel but it is found that if there is a high percentage of chromiumwhich will cause the metal to resist oxidation the emission of heattherefrom is lessened and the object of the invention is to provide acase or sheathing of non-oxidizable chrome metal with a surface thatwill quickly and readily dissipate or emit the heat generated in theinterior of the heating element. v

According to the invention the metal case or sheathing of the heatingelement is made from a chrome iron or steel having a high percentage ofchromium to render it non oxidizable the surface being coated with afine coating or layer of heat emitting material such as copper or ironoxidized by the application'of heat.

The'metal case or sheathing may be of known construction or of theconstruction described in my application Number 511,909, filedconcurrently herewith.

It is made of a chrome iron or steel having about 20% of chromium torender it nonoxidizable with or without nickel. The surface preferablyafter the case is constructed is coated by plating or spraying with alayer of copper and is subsequently heated to a degree suflicient tooxidize the surface of 1 copper (say 600 to 700 0.).

The invention may be applied to elements I either annular, straight orfiat.

What'l claim as my invention and desire to protect by Letters Patentis 1. An electric heating element of the type referred to constructedwith a sheathing of highly resisting non-oxidizable chrome metal theexterior surface of which is coated with a fine layer of metallic oxide.

2. An electric heating element of the type referred to constructed witha case of highly resisting non-oxidizable chrome metal the exteriorsurface of" which is coated with a fine layer of copper oxide.

my hand this 9th day of January 1931.

GEORGE BRAY.

